1. Field of the Invention and Related Art Statement
This invention relates to a recording and reproducing apparatus provided in each data block such as a sector with a secret information number as a data protecting means for inhibiting information recorded in such optical recording medium as an optical card from being read out.
Among information recording and reproducing apparatus for recording and/or reproducing information in an information recording medium are such magnetic recording medium as a floppy disc or magnetic card and such optical recording medium as an optical disc or optical card. Optical discs and optical cards are optical recording media. They can not be re-written but are so large in the memorizing capacity as to be considered to have a wide application range for the optical discs to record image information or to preserve writings and for the optical cards as bank deposit pass-books, portable maps or prepaid cards used for shopping or the like.
Particularly, the optical card is so portable as to be considered to be used to record such personal private information as individual health controlling information. Therefore, countermeasures of protecting information peculiar to an individual from being seen by others are being investigated by encoding the information. In the publications of Japanese Patent Applications Laid Open Nos. 286176/1989 and 192978/1988 is disclosed a method wherein data other than the inherent information are recorded as additional information in a part within a sector of an optical card or photomagnetic disc.
In the publication of Japanese Patent Application Laid Open No. 192978/1988, additional information is added to each data block so that errors may be corrected in the line direction and column direction to improve the error correcting function.
Also, in the publication of Japanese Patent Application Laid Open No. 286176/1989, a track number is added to each sector and an error correcting code is added to the sector number in recording them so that the track number and sector number may be read out at a probability higher than in ordinary data.
In the method wherein the information to be kept secret relating to an individual is encoded and recorded so as to be decoded when it is to be reproduced, there are problems that such hard formation as a logical circuit of encoding/decoding the information will be required and the cost will be high. In case it is not of a hard formation, a soft formation will be made by the program by using a microcomputer or the like controlling the recording and reproducing apparatus, the process will take time and the access time will be likely to increase.
In the publications of Japanese Patent Applications Laid Open Nos. 286176/1989 and 192978/1988, the example of recording the track number, sector number and disc discriminating information is only disclosed but nothing is mentioned of the protection of the information.
By the way, in the now extensively prevalent cash card, a secret information number is input in using the card. Such secret information number is not to protect the information mentioned in the card but is to identify whether the person using the card is the owner of the card so that only the owner of the card may have access to the card. Therefore, when even a third person can input the secret information number, he will be able to unjustly have access to the card and will be likely to cause a great damage to the owner of the card.